In case of endoluminal operations two contrasting needs are felt for catheters: great axial compression stiffness but also great flexibility. The axial compression stiffness allows the catheter distal section to be readily responsive to the movements caused on the proximal section by the operator. On the other hand, the flexibility allows the catheter to find its way through the blood vessels, which is often a tortuous path, in the simplest and less traumatic way for the patient.
This need for flexibility is particularly felt for the catheter distal section which is intended to reach those vessels which, among those being run through by the catheter, are of a smaller diameter.
For the same reasons, this need for flexibility is even more felt for the catheter tip.
Another requirement for the catheter tip is to fair the front profile of the catheter from its minimum diameter, such as that of the lumen with a guide wire running therein, to its maximum diameter available in the distal section, such as that of a sheath holding a stent in its state of maximum radial collapse.
A further requirement for the catheter tip is to ensure that the flexibility of the distal end in the proximal direction will change as evenly as possible.
A still further need for both the catheter and its tip is to ensure their mutual adherence, also in most severe usage conditions, in order to prevent any disjunction between the catheter main body and its tip.
Catheter tips are known to be added to the catheter main body by overmoulding. These known tips are obtained by means of a mould reproducing their shape, inside which the distal end of the tube being the catheter main body is inserted. A plastic material is then injected into the mould. While polymerizing, it adheres to the outer surface of the catheter main body.
The above catheter tips are known to have poor flexibility which abruptly changes at the point where, inside the tip, the tube being the catheter main body ends.
Due to its almost mere chemical nature, the adherence of these tips to the catheter main bodies is also known to be negatively affected, and in some cases even impaired, by a non-optimum preparation of the respective polymeric materials.